Motion Sensor Lights Indoors
Toilets, Store Rooms, Wardrobes and Corridors

Which rooms suit motion lighting indoors

Motion lighting earns its place where hands are full, visits are short or the light is often left on by mistake. It annoys people where they stay put. A quick test: if you would normally switch the light on, do one thing and leave within a few minutes, the room is a good candidate.

Motion, occupancy and presence are different questions

Smart home apps use three similar-sounding words for three different things. Home Assistant’s documentation describes them as device classes: motion shows whether motion is detected, occupancy whether a room or area is occupied, and presence whether someone is home. The difference matters when you buy a sensor.

• Motion sensors, usually passive infrared (PIR), notice a warm body moving across their view. They are cheap, run for a long time on batteries and react fast, but they cannot tell that someone sitting still is still there.
• Occupancy or presence sensors sold for rooms use radar or similar techniques designed to notice much smaller movements, so a person who is reading or sitting is less likely to be missed. They generally need mains or USB power and take more setting up.
• Home or away presence is a different idea again: usually phones joining the WiFi or sharing location, used for whole-house routines rather than one room’s light.

The toilet problem: the light goes off while you sit still

This is the single most common complaint about indoor motion lights. A PIR sensor mounted to see the doorway catches you walking in, then sees nothing once you sit, and the timer runs out. There are four ways round it, and they can be combined.

1. A longer delay. The simplest fix, at the cost of the light staying on after you leave.
2. Better placement. A sensor that can see the area where people sit, not only the door, catches small movements more often.
3. A door sensor as the second input. The light turns on with motion and only turns off when the door has opened again and no motion follows; a routine in the app joins the two.
4. A presence sensor in place of the PIR, for a bathroom that is used for longer stays.

Whatever you choose, keep the wall switch working, so anyone can override it.

Three kinds of hardware

The battery route is popular in finished homes because nothing in the ceiling changes: the sensor tells the hub, and the hub tells a smart switch or smart bulb to act. If the light in that room is on an ordinary switch today, the smart switch vs smart bulb comparison helps you decide which end to make smart.

The three settings that decide whether it annoys you

Most of the difference between a motion light you like and one you rip out is in the settings, not the hardware.

• Timeout. How long the light stays on after the last movement. It is set in the app or on the sensor; as one example, Aqara says the timeout of its Motion Sensor P1 can be configured from 1 to 200 seconds in its app. Start longer than you think you need and shorten it.
• Light level. Many sensors include a light sensor so the light only comes on when the room is dark. Aqara’s example rule for the same sensor is to turn on the light when motion is detected and brightness is below 30 lux, a threshold it says can be configured in the app. In practice you adjust it until the light stays off on a bright afternoon.
• Sensitivity or zone. Lower sensitivity, or a narrower view, stops the corridor light firing every time someone walks past the open door.

Placement rules indoors

• Aim the sensor so people walk across its view rather than straight at it; PIR sensors tend to react faster to sideways movement.
• Keep it away from aircon outlets, sunlit windows and hot appliances, which change the heat it sees.
• Do not let it look out of an open door into a corridor, or every passer-by turns the room on.
• In homes with cats or dogs, mount higher and angle down, or lower the sensitivity.
• Keep battery sensors where they can be reached for battery changes without a ladder, if possible.

Wardrobes, store rooms and cabinets

Inside wardrobes and store rooms the light is usually an LED strip or puck light rather than a ceiling fitting. Hinged doors can use a door switch; sliding doors and walk-in wardrobes need a motion sensor, because there is no hinge to trigger. The cabinet and wardrobe LED lighting guide covers drivers, profiles and planning with the carpenter. If the strip is going to be on a smart controller anyway, the smart LED strip guide explains how a sensor can drive it through the app.

For a store room you rarely visit, a stick-on rechargeable sensor light is often enough, and nobody has to touch the ceiling.

Night mode: dim and warm after bedtime

The same motion that should give a full light at seven in the evening should give a soft, warm one at three in the morning. Most hubs let a routine choose the brightness by time of day, if the light is dimmable. A low night level along the route from bedroom to toilet is one of the most useful changes for older parents; the smart home guide for elderly parents covers the rest of that route, and the 2-way smart switch guide for staircases covers stairs, where a motion trigger works best as an extra rather than the only control.

Always keep a manual override

Sensors fail, batteries run flat and hubs restart. A light that can only be controlled by a sensor is a light that will one day leave someone in the dark. Keep the wall switch in place and working, and decide what it does: many smart switches let a press override the sensor until the next time the room empties. Add a way to pause the automation for cleaning days or when guests stay.

Motion sensors used for lighting are not an alarm. A sensor that also sends phone alerts when you are away is a different use, with different placement; the guide to home alarm sensor types explains that side.

Bathrooms: steam, splashes and mains fittings

Bathrooms are the hardest room for sensors. Keep battery sensors out of shower spray and away from the ventilation fan outlet, and expect condensation to shorten their life. Fittings and sensors wired into the bathroom lighting must suit a damp space; the bathroom lighting guide explains the ratings and zones. Any mains electrical work, such as a new power point, a change at the distribution board or a hardwired switch that needs new wiring, must be done by an electrical contractor registered with Suruhanjaya Tenaga.

How we help

We install battery motion sensors, link them to your hub, and set up the timeout, light-level and night routines room by room. For smart switches and anything wired into the mains, we supply the devices and set up the app, and the switch or wiring work is done by an electrical contractor registered with Suruhanjaya Tenaga that we coordinate. We do the smart device, app and low-voltage side of the job. For the full range of what we set up, see the smart home installation page.

Sources & references

• Aqara Motion Sensor P1 product page: configurable detection timeout, built-in light sensor and an example light-level rule.
• Home Assistant documentation: binary sensor device classes: motion, occupancy and presence.